scholarly journals The break-up of free films pulled out of a pure liquid bath

2016 ◽  
Vol 811 ◽  
pp. 499-524 ◽  
Author(s):  
Lorène Champougny ◽  
Emmanuelle Rio ◽  
Frédéric Restagno ◽  
Benoit Scheid
Keyword(s):  
Silicone Oil ◽  
Quantitative Agreement ◽  
Van Der Waals Interactions ◽  
Pure Liquid ◽  
Film Rupture ◽  
Wide Range ◽  
Free Liquid Film ◽  
Break Up ◽  
The Moment ◽  
Free Films

In this paper, we derive a lubrication model to describe the non-stationary free liquid film that is created when a vertical frame is pulled out of a liquid reservoir at a given velocity. We here focus on the case of a pure liquid, corresponding to a stress-free boundary condition at the liquid/air interfaces of the film, and thus employ an essentially extensional description of the flow. Taking into account van der Waals interactions between the interfaces, we observe that film rupture is well defined in time as well as in space, which allows us to compute the critical thickness and the film height at the moment of rupture. The theoretical predictions of the model turn out to be in quantitative agreement with experimental measurements of the break-up height of silicone oil films in a wide range of pulling velocities and supporting fibre diameters.

Industrial Labour Force of Russia in 20-30s of XX Century in Russian Historiography

2020 ◽  
pp. 431-449
Author(s):  
Oleg V. Shekatunov ◽  
Konstantin G. Malykhin
Keyword(s):  
Labour Force ◽  
Historical Period ◽  
Russian Industry ◽  
Wide Range ◽  
Scientific Papers ◽  
Potential Formation ◽  
The Moment ◽  
Force Potential ◽  
Modern Russian

The article is devoted to the specifics of studying the industrial labour force of Russia in the 1920s - 1930s in Russian historiography. The various stages of study from the 1920s through the 1930s and up to the last years are concerned. The relevance of the study is due to several factors. These include contradictions in the assessments of Bolshevik modernization of the 1920s and 1930s; projected labour force shortages in modern Russia; as well as the existing labour force shortage in industry at the moment. This determines the relevance of studying the historical period, which was characterized by the most acute personnel problems in the country. The novelty of the study is due to the fact that in modern Russian historiography there is no holistic, integrated view of the problems of the labour force potential formation of Russian industry in the 1920s and 1930s. It is noted that there is no research aimed at analyzing the historiography of these problems. The main stages of the study of industrial labour force are highlighted. The analysis of scientific works correlated with each stage of the study of the topic is performed. The problems and methodology of each stage are considered. A review of a wide range of scientific papers both articles and thesis is presented.

Potential Triazole-based Molecules for the Treatment of Neglected Diseases

2019 ◽  
Vol 26 (23) ◽  
pp. 4403-4434 ◽  
Author(s):  
Susimaire Pedersoli Mantoani ◽  
Peterson de Andrade ◽  
Talita Perez Cantuaria Chierrito ◽  
Andreza Silva Figueredo ◽  
Ivone Carvalho
Keyword(s):  
Effective Treatment ◽  
Chagas Disease ◽  
Medicinal Chemistry ◽  
Biological Activities ◽  
Neglected Diseases ◽  
Triazole Derivatives ◽  
Wide Range ◽  
The World ◽  
Great Relevance ◽  
The Moment

Neglected Diseases (NDs) affect million of people, especially the poorest population around the world. Several efforts to an effective treatment have proved insufficient at the moment. In this context, triazole derivatives have shown great relevance in medicinal chemistry due to a wide range of biological activities. This review aims to describe some of the most relevant and recent research focused on 1,2,3- and 1,2,4-triazolebased molecules targeting four expressive NDs: Chagas disease, Malaria, Tuberculosis and Leishmaniasis.

scholarly journals EXPRESS: Overcoming the Cold Start Problem of CRM using a Probabilistic Machine Learning Approach

2021 ◽  
pp. 002224372110329
Author(s):  
Nicolas Padilla ◽  
Eva Ascarza
Keyword(s):  
Machine Learning ◽  
Cold Start ◽  
Customer Relationship ◽  
Exponential Families ◽  
Modeling Framework ◽  
Wide Range ◽  
The Moment ◽  
Probabilistic Machine Learning ◽  
Marketing Actions ◽  
Cold Start Problem

The success of Customer Relationship Management (CRM) programs ultimately depends on the firm's ability to identify and leverage differences across customers — a very diffcult task when firms attempt to manage new customers, for whom only the first purchase has been observed. For those customers, the lack of repeated observations poses a structural challenge to inferring unobserved differences across them. This is what we call the “cold start” problem of CRM, whereby companies have difficulties leveraging existing data when they attempt to make inferences about customers at the beginning of their relationship. We propose a solution to the cold start problem by developing a probabilistic machine learning modeling framework that leverages the information collected at the moment of acquisition. The main aspect of the model is that it exibly captures latent dimensions that govern the behaviors observed at acquisition as well as future propensities to buy and to respond to marketing actions using deep exponential families. The model can be integrated with a variety of demand specifications and is exible enough to capture a wide range of heterogeneity structures. We validate our approach in a retail context and empirically demonstrate the model's ability at identifying high-value customers as well as those most sensitive to marketing actions, right after their first purchase.

Rheo-Optics Studies in the Development of Hybrid Liquid Crystalline Based Mwir Polarizers

1999 ◽  
Vol 559 ◽  
Author(s):  
P.T. Mather ◽  
W. Barnes ◽  
P.J. Hood ◽  
T.J. Bunning
Keyword(s):  
Liquid Crystalline ◽  
Flow Behavior ◽  
Optical Microscope ◽  
Processing Technique ◽  
Strain Rates ◽  
Alignment Layer ◽  
Small Pitch ◽  
Wide Range ◽  
Measured Polarization ◽  
Free Films

ABSTRACTWe present here a rheo-optical study of the flow behavior of two cholesteric liquid crystals, one with a large pitch and one with a small pitch. The large pitch compound has been investigated as a possible fixed wavelength polarizer in the mid-wavelength infra-red region (3-5 micron). The investigation of these compounds is driven by their low melt viscosity and ability to vitrify order, and thus functionality, into films with a wide range of thickness. In our attempts to obtain consistent thin films with reproducible contrast ratios, we explored the defect textures of both compounds under a polarizing optical microscope. These materials were sheared at various strain rates and at various temperatures in an attempt to determine the best processing window for defect free films. The pitch lengths of the two materials investigated were 160 and 1330 nm. The flow behavior of the large pitch material resembles a pure nematic with defect refinement taking place under flow. The short pitch material exhibited the typical Grandjean oily streaks upon shearing followed by coarsening. Observations made during this rheological study were used to identify a processing technique for the large pitch materials. Upon application of a conventional buffed alignment layer, films with consistent quality were routinely made. The measured polarization contrast of >70:1 exceeds the values obtained from state-of-the art commercial polarizers in this wavelength regime.

Films in narrow tubes

2014 ◽  
Vol 762 ◽  
pp. 68-109 ◽  
Author(s):  
Georg F. Dietze ◽  
Christian Ruyer-Quil
Keyword(s):  
Liquid Film ◽  
Silicone Oil ◽  
Low Frequency ◽  
Cylindrical Tube ◽  
Film Coating ◽  
Two Phase ◽  
Integral Boundary ◽  
Tube Cross Section ◽  
Free Liquid Film ◽  
Low Dimensional

AbstractWe consider the axisymmetric arrangement of an annular liquid film, coating the inner surface of a narrow cylindrical tube, in interaction with an active core fluid. We introduce a low-dimensional model based on the two-phase weighted residual integral boundary layer (WRIBL) formalism (Dietze & Ruyer-Quil, J. Fluid Mech., vol. 722, 2013, pp. 348–393) which is able to capture the long-wave instabilities characterizing such flows. Our model improves upon existing works by fully representing interfacial coupling and accounting for inertia as well as streamwise viscous diffusion in both phases. We apply this model to gravity-free liquid-film/core-fluid arrangements in narrow capillaries with specific attention to the dynamics leading to flooding, i.e. when the liquid film drains into large-amplitude collars that occlude the tube cross-section. We do this against the background of linear stability calculations and nonlinear two-phase direct numerical simulations (DNS). Due to the improvements of our model, we have found a number of novel/salient physical features of these flows. First, we show that it is essential to account for inertia and full interphase coupling to capture the temporal evolution of flooding for fluid combinations that are not dominated by viscosity, e.g. water/air and water/silicone oil. Second, we elucidate a viscous-blocking mechanism which drastically delays flooding in thin films that are too thick to form unduloids. This mechanism involves buckling of the residual film between two liquid collars, generating two very pronounced film troughs where viscous dissipation is drastically increased and growth effectively arrested. Only at very long times does breaking of symmetry in this region (due to small perturbations) initiate a sliding motion of the liquid film similar to observations by Lister et al. (J. Fluid Mech., vol. 552, 2006, pp. 311–343) in thin non-flooding films. This kickstarts the growth of liquid collars anew and ultimately leads to flooding. We show that streamwise viscous diffusion is essential to this mechanism. Low-frequency core-flow oscillations, such as occur in human pulmonary capillaries, are found to set off this sliding-induced flooding mechanism much earlier.

Viscosity Effect on Thermocapillary Rupture of Falling Liquid Films

2010 ◽  
Author(s):  
Dmitry Zaitsev ◽  
Andrey Semenov ◽  
Oleg Kabov
Keyword(s):  
Heat Flux ◽  
Film Thickness ◽  
Inclination Angle ◽  
Theoretical Models ◽  
Liquid Films ◽  
Liquid Viscosity ◽  
Inclined Plate ◽  
Film Rupture ◽  
Generalize Data ◽  
Wide Range

Rupture of a subcooled liquid film flowing over an inclined plate with a 150×150 mm heater is studied for a wide range of liquid viscosity (dynamic viscosity μ = (0.91–17.2)x10−3 Pa·s) and plate inclination angle with respect to the horizon (Θ = 3–90 deg). The main governing parameters of the experiment and their respective values are: Reynolds number Re = 0.15–54, heat flux q = 0–224 W/cm2. The effect of the heat flux on the film flow leads to the formation of periodically flowing rivulets and thin film between them. As the heat flux grows the film thickness between rivulets gradually decreases, and, upon reaching a certain threshold heat flux, qidp, the film ruptures in the area between the rivulets. The threshold heat flux increases with the flow rate of liquid and with the liquid viscosity, while the plate inclination angle has little effect on qidp. Criterion Kp, which is traditionally used in the literature to predict thermocapillary film rupture, was found to poorly generalize data for high viscous liquids (ethylene glycol, and aqueous solutions of glycerol) and also data for Θ≤45 deg. The criterion Kp was modified by taking into account characteristic critical film thickness for film rupture under isothermal conditions (no heating), deduced from existing theoretical models. The modified criterion has allowed to successfully generalize data for whole ranges of μ, Re, Θ and q, studied.

Numerical Jet Atomization: Part II — Modeling Information and Comparison With DNS Results

2006 ◽  
Author(s):  
P. A. Beau ◽  
T. Me´nard ◽  
R. Lebas ◽  
A. Berlemont ◽  
S. Tanguy ◽  
...  
Keyword(s):  
Level Set ◽  
Volume Fraction ◽  
Computing Time ◽  
Mass Conservation ◽  
Liquid Volume ◽  
Liquid Density ◽  
Wide Range ◽  
The Mean ◽  
Break Up ◽  
Primary Break

The main objective of our work is to develop direct numerical simulation tools for the primary break up of a jet. Results can help to determine closure relation in the ELSA model [1] which is based on a single-phase Eulerian model and on the transport equation for the mean liquid/gas interface density in turbulent flows. DNS simulations are carried out to obtain statistical information in the dense zone of the spray where nearly no experimental data are available. The numerical method should describe the interface motion precisely, handle jump conditions at the interface without artificial smoothing, and respect mass conservation. We develop a 3D code [2], where interface tracking is ensured by Level Set method, Ghost Fluid Method [3] is used to capture accurately sharp discontinuities, and coupling between Level Set and VOF methods is used for mass conservation [4]. Turbulent inflow boundary conditions are generated through correlated random velocities with a prescribed length scale. Specific care has been devoted to improve computing time with MPI parallelization. The numerical methods have been applied to investigate physical processes that are involved in the primary break up of an atomizing jet. The chosen configuration is close as possible of Diesel injection (Diameter D = 0.1 mm, Velocity = 100m/s, Liquid density = 696kg/m3, Gas density = 25kg/m3). Typical results will be presented. From the injector nozzle, the turbulence initiates some perturbations on the liquid surface, that are enhanced by the mean shear between the liquid jet and the surrounding air. The interface becomes very wrinkled and some break-up is initiated. The induced liquid parcels show a wide range of shapes. Statistics are carried out and results will be provided for liquid volume fraction, liquid/gas interface density, and turbulent correlations.

scholarly journals A Review on Additive Manufacturing of Micromixing Devices

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 73
Author(s):  
Marina Garcia-Cardosa ◽  
Francisco-Javier Granados-Ortiz ◽  
Joaquín Ortega-Casanova
Keyword(s):  
Life Cycle ◽  
Additive Manufacturing ◽  
High Performance ◽  
Future Prospects ◽  
High Quality ◽  
Printing Technology ◽  
Wide Range ◽  
The Moment ◽  
Manufacturing Technologies

In recent years, additive manufacturing has gained importance in a wide range of research applications such as medicine, biotechnology, engineering, etc. It has become one of the most innovative and high-performance manufacturing technologies of the moment. This review aims to show and discuss the characteristics of different existing additive manufacturing technologies for the construction of micromixers, which are devices used to mix two or more fluids at microscale. The present manuscript discusses all the choices to be made throughout the printing life cycle of a micromixer in order to achieve a high-quality microdevice. Resolution, precision, materials, and price, amongst other relevant characteristics, are discussed and reviewed in detail for each printing technology. Key information, suggestions, and future prospects are provided for manufacturing of micromixing machines based on the results from this review.

scholarly journals LDA method in psychological assessment of text comprehension

2021 ◽  
Author(s):  
С.А. Свердлов
Keyword(s):  
Psychological Assessment ◽  
Text Comprehension ◽  
Advantages And Disadvantages ◽  
Text Understanding ◽  
Modern Psychology ◽  
Wide Range ◽  
Psychology Pedagogy ◽  
The Moment ◽  
Comparison Of The Results ◽  
Different Content

Проблема понимания текстов и способов его оценки является одной из фундаментальных для современной психологии, педагогики, лингвистики. На настоящий момент имеется большое количество попыток выработки метода оценки понимания текстов, который бы отражал объективную картину интериоризации материала текста читателем, и вместе с тем подходил бы для стандартизации и применения на широком диапазоне текстов различного содержания и структуры, по возможности с минимальными затратами ресурсов оценщика и самого читателя. В настоящей статье раскрываются современные подходы к оценке понимания текстов, их преимущества и недостатки, и формулируется новый перспективный метод оценки понимания текстов, использующий в своём основании модель Латентного размещения Дирихле. Данный метод затем проходит исследование валидности через сравнение результатов его применения и наиболее часто используемых современных методов оценки понимания текстов, делается вывод о его применимости в реальных условиях и перспективах использования в спектре прикладных задач. The problem of understanding texts and methods of assessing it is one of the fundamental for modern psychology, pedagogy, linguistics. At the moment, there are a large number of attempts to develop a method for assessing the understanding of texts, which would reflect an objective picture of the internalization of the material of the text by the reader, and at the same time would be suitable for standardization and application on a wide range of texts of different content and structure, if possible with minimal expenditure of resources of the evaluator and the reader himself. This article reveals modern approaches to assessing text understanding, their advantages and disadvantages, and formulates a new promising method for assessing text understanding, based on the Dirichlet Latent Placement model. This method then goes through a validity study through a comparison of the results of its application and the most commonly used modern methods for assessing text understanding, a conclusion is made about its applicability in real conditions and the prospects for use in a range of applied problems.

scholarly journals MAIN PROBLEMS OF TRANSITION OF UNIVERSITIES TO REMOTE LEARNING UNDER MODERN CONDITIONS OF FUNCTIONING

2020 ◽  
pp. 52-57
Author(s):  
Т. Р. Магомаев
Keyword(s):  
Distance Learning ◽  
Negative Impact ◽  
Educational Institution ◽  
Educational Process ◽  
High Quality ◽  
Higher Education System ◽  
Professional Activities ◽  
Wide Range ◽  
Information And Communication ◽  
The Moment

В современных условиях функционирования системы высшего образования целью внедрения дистанционного обучения является организация качественного учебно-воспитательного процесса «на расстоянии» с использованием новейших информационно-коммуникационных средств и открытым доступом к образовательным ресурсам. Именно такая форма обучения может быстро адаптироваться к требованиям информационного общества и подготовить будущего специалиста к вызовам цифровой среды. В сочетании с традиционными формами, дистанционное образование в высшем учебном заведении может предоставить широкий спектр образовательных услуг как для абитуриентов и студентов для приобретения необходимых навыков и умений для будущей профессиональной деятельности, так и для преподавателей с целью повышения квалификации. На данный момент основными проблемами внедрения качественного свободного образовательного пространства является отсутствие технической и финансовой поддержки, законодательной основы дистанционного обучения, и это является ведущим фактором сдерживания развития технологий в вузе. Отсутствуют специально подготовленные к работе в дистанционном режиме квалифицированные преподаватели. Однако, учитывая готовность вузов осуществлять обучение преподавателей для работы в дистанционном режиме, негативное влияние этого фактора в ближайшее время может быть устранено. При условии решения вышеописанных проблем будет создано эффективное дистанционное обучение, которое всесторонне раскроет потенциал студента, учитывая как индивидуальные, так и общечеловеческие потребности. In modern conditions of functioning of the higher education system, the goal of introducing distance learning is to organize a high-quality educational process “at a distance” using the latest information and communication tools and open access to educational resources. It is this form of training that can quickly adapt to the requirements of the information society and prepare the future specialist for the challenges of the digital environment. In combination with traditional forms, distance education in a higher educational institution can provide a wide range of educational services for both applicants and students to acquire the necessary skills for future professional activities, and for teachers to improve their skills. At the moment, the main problems in introducing high-quality free educational space is the lack of technical and financial support, the legislative basis of distance learning, and this is a leading factor in curbing the development of technology at the university. There are no qualified teachers specially prepared for working in remote mode. However, given the willingness of universities to train teachers to work remotely, the negative impact of this factor in the near future can be eliminated. Subject to the solution of the above problems, an effective distance learning will be created that will comprehensively reveal the student’s potential, taking into account both individual and universal needs.

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